Energy Efficient Transmission Research Articles

Active ballistic orbital transport in Ni/Pt heterostructure

Orbital current, defined as the orbital character of Bloch states in solids, can travel with larger coherence length through a broader range of materials than its spin counterpart, facilitating a robust, higher density and energy efficient information transmission. Hence, active control of orbital transport plays a pivotal role in the progress of the evolving field of quantum information technology. Unlike spin angular momentum, orbital angular momentum couples to phonon angular momentum efficiently via orbital-crystal momentum (L-k) coupling, allowing us to control orbital transport through crystal field potential mediated angular momentum transfer. Here, leveraging the orbital dependant efficient L-k coupling, we have experimentally demonstrated the active control of orbital current velocity in Ni/Pt heterostructure. We observe terahertz emission from Ni/Pt heterostructure via long-range ballistic orbital transport, as evidenced by the delay, and chirping in the emitted THz pulse correlating with increased Pt thickness. Additionally, we also have identified a critical energy density required to overcome collisions in orbital transport, enabling a swifter flow of orbital current. Femtosecond light driven active control of the ballistic orbital transport lays the foundation for the development of dynamic optorbitronics for transmitting information over extended distance.

Study of operation mode and breakdown characteristics for multi-stage gas switch

Multi-stage gas switches (MSGSs) are widely used in megavolt pulsed power systems due to their advantages of high withstand voltage, fast establishing time and relatively high operating frequency. Multiple operation modes, which are induced by the different breakdown sequences at each stage, are found to affect the breakdown characteristics of the gas switch. Based on the theoretical analysis of the working principle, the classification of the operation mode and the factors determining the operation mode of the MSGS are proposed. Methods for investigating the output waveform for MSGS are established by simulating lumped parameters and studying the breakdown time sequence of individual stages. In comparison with the intended mode of operation, the disadvantages of the unintended modes of operation for MSGS, including error-breakdown and non-triggering mode, are revealed. For unintended modes, the distortion of the output waveform, which determines the efficiency of energy transmission through the switch and the increased delay time jitter, which determines the synchronization of the gas switch, are further investigated. The possibility of non-triggering and its mechanism on surface flashovers induced by drifting electrons are also analyzed. Based on this study, design principles and methods are proposed to ensure the intended operation of the MSGS.

Joint subchannel power allocation for downlink NOMA systems based on quantum carnivorous plant algorithm

Currently, most existing research on non-orthogonal multiple access (NOMA) systems converts power allocation into two independent procedures, i.e., inter-subchannel power allocation and intra-subchannel power allocation. However, improper inter-subchannel power allocation will adversely affect the power allocation process of intra-subchannel. If the power allocations of inter-subchannel and intra-subchannel are optimized simultaneously, it usually needs high computational complexity, and is hard to obtain an optimal solution. To tackle this issue, this paper studies the joint subchannel power allocation for NOMA systems and proposes a new intelligent algorithm called quantum carnivorous plant algorithm (QCPA) for simultaneously optimizing inter-subchannel and intra-subchannel power allocations. Analysis of the convergence of QCPA verified its superior performance on the test functions. By utilizing the optimal solution obtained by QCPA as the power allocation scheme, energy efficiency and sum transmission rate in NOMA systems are significantly increased compared to existing traditional power allocation methods. The results above demonstrate that QCPA effectively addresses test functions and the power allocation problem for NOMA. QCPA possesses favorable convergence in comparison to other comparison algorithms and methods.

Flexible Ultrasonic‐Induced Wireless Energy Conversion Technology in Implantable Biomedicine

AbstractNumerous associated challenges arise with the advancement and continuous improvement of implantable medical devices, such as the frequent requirement for battery replacement. The flexible ultrasonic‐induced wireless energy conversion (UWEC) technology has garnered significant interest due to its superior energy transmission efficiency, safety, and biocompatibility compared to traditional electromagnetic wireless energy conversion technology. This paper provides a comprehensive review of the recent advancements in two types of flexible UWEC technologies, triboelectric nanogenerators, and piezoelectret nanogenerators, with a focus on their applications in implantable medical treatments. First, the energy conversion principles and general materials of flexible UWEC are presented. Then, the research and application of flexible UWEC devices are introduced in detail based on their medical functions. At the end of this review, perspectives and opportunities are discussed.

Evaluating battery electric vehicle usage in the EU: A comparative study based on member state energy mixes

The transport sector is undergoing a major transformation, as battery electric vehicles (BEV) are gaining ground. Therefore, assessing the sustainability aspects of their use is crucial to obtaining a clear picture of the sector. This article aims to meet this requirement by using European Union (EU) data for the period 2011 to 2021 and focuses not only on EU-27 aggregates but also on each member state separately. For the evaluation, a well-to-wheel (WTW) method was used to calculate two parameters: energy-specific CO2 emissions (ε) and total efficiency of energy conversions, transmission, and battery (ηtotal). For these values, the annual electricity mixes of the countries were tracked in 5 + 1 categories (combined cycle gas turbine (CCGT), thermal power plant, biofuels, nuclear power plant (NPP), renewables, and imports). The calculated results were illustrated by sustainability matrices describing the former and current positions of the countries. The EU-27 aggregate achieved a 0.04 increase (from 0.37 to 0.41) in total efficiency and a 29 gCO2/MJmotion decrease (from 113 to 84 gCO2/MJmotion) during the period. This ε value for 2021 was around half the world average. However, very significant differences were identified between member states, which are also assessed in the article with special emphases on the five most populated EU countries (Germany, France, Italy, Spain, and Poland).

Energy Efficient Transmission Strategy for Mobile Edge Computing Network in UAV-Based Patrol Inspection System

Energy Efficient Transmission Strategy for Mobile Edge Computing Network in UAV-Based Patrol Inspection System

A Low-Voltage Self-Starting Boost Converter Using MPPT with Pulse Multiplication for Energy Harvesting

A single-inductor, low-voltage, three-step self-starting boost converter is proposed for photovoltaic (PV) energy harvesting. In order to enhance energy transfer efficiency, a variable-step Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) scheme has been devised based on a novel pulse multiplication technique. Upon overcoming the speed and accuracy limitations, the maximum power point (MPP) of the PV model is accurately tracked. In the boost converter, the average inductor current is utilized to implement closed-loop control of the MPPT loop, enhancing the stability of the tracking process and enabling efficient energy transmission. Finally, the boost converter is implemented using a 0.18 μm CMOS process, which is capable of self-starting and maintaining stable operations at input voltages ranging from 90 mV to 300 mV, achieving a peak efficiency of 93%.

Feasibility of high temperature superconducting cables for energy harvesting in large space-based solar power satellite applications: Electromagnetic, thermal and cost considerations

The aim of this paper is to present feasibility of application of High Temperature Superconducting (HTS) cables for Space-Based Solar Power (SBSP) application. SBSP is a promising technology that can deliver an infinite amount of clean and eco-friendly energy to the Earth. To deliver the harvested solar energy to the power systems on Earth, efficient energy transmission is critically important. To address the challenges of conventional transmission means, an ideal solution would be using HTS cables. In this research, the design procedure of a Direct Current (DC) HTS cable considering electromagnetic, thermal, and cost constraints is presented. The study considered a 2 MW bipolar DC HTS cable in five operational temperatures: 20 K, 30 K, 50 K, 65 K, and 77 K. The results were showed that the cost and weight of the designed HTS cables were increased by operational temperature increase. However, the cooling cost of HTS cable in higher temperatures, was less than lower temperatures. Also, the total efficiency of the HTS cable and cooling system were increased, when operational temperatures were changed from 20 K to 77 K, from 99.70% to 99.97%, respectively.

Prediction of thermal contact resistance for reusable heat-pipe cooled thermal protection system based on an inverse thermo-mechanical coupling method

Thermal contact resistance (TCR) is a critical characteristic on increasing or decreasing thermal energy transmission efficiency between two bodies in thermal management systems. However, it is difficult to accurately determine the thermal contact resistance in actual engineering structures, due to the complicated influence factors, such as pressure, temperature, and physical properties. In the work, a new method is presented to estimate the thermal contact resistance for a three-dimensional (3D) reusable heat-pipe cooled thermal protection system based on boundary measurements, by solving transient inverse thermo-mechanical coupling problems. Moreover, the thermal contact resistance varies with interface pressure, temperature, and spatial position, which is more practical and challenging. The thermo-mechanical coupling analysis is conducted by the finite element method, and the inversion is carried out by the gradient-based algorithm. First, the present method is validated by identifying the constant TCR, based on the available experimental data. Then, the thermal contact resistance with the functional form in the 3D reusable thermal protection system is accurately estimated. Finally, the convergence stability and robustness of the proposed method are evaluated, by considering the effects of initial guess value and measurement error, respectively. The accurate determination of thermal contact resistance of the reusable thermal protection system effectively avoids the overweight of aircraft and improves its utilization. The present work provides a novel approach for the determination of thermal contact resistance in actual engineering applications.

Design of Magnetic Coupler for AUV Wireless Charging and Its Electromagnetic Field Simulation

The magnetic coupler is one of the important components of wireless charging system, and its coupling coefficient directly influences the energy transmission efficiency. This paper designs a magnetic coupler for Autonomous Underwater Vehicle(AUV) wireless charging in the marine environment. Firstly, the eddy current effect during energy transmission of the magnetic coupler under seawater conditions is analyzed, and the equivalent model of the wireless charging system is compensated and corrected. Then, the genetic-BP neural network algorithm is used to determine the relevant structural parameters of the magnetic coupler. Finally, the electromagnetic field simulation analysis of the offset phenomenon between the transmitting and receiving sides of the magnetic coupler is carried out based on ANSYS MAXEWLL software.The results show that the coupling coefficient of the magnetic coupler under normal operation is 0.87, and if there is a 10mm radial offset (or 5 ° circumferential offset), the coupling coefficient will decrease to 0.74 (or 0.78), which provides a reference basis for the subsequent offset fault-tolerant design of the AUV wireless charging system.

Intelligent fault diagnosis of railway pantograph using a novel graph construction methodology

Railway pantographs provide power for railway vehicles by conducting electrical energy from overhead catenary. The failure of the pantograph tends to damage the contact quality between the pantograph and the catenary, reducing the transmission efficiency of electric energy. Hence, fault diagnosis of pantograph plays a significant role in expanding the service life of railway vehicles. In this work, a novel graph construction method is proposed for the fault diagnosis of pantographs combined with a graph neural network (GNN). In the graph construction method, 1D load signals collected from the test pantograph are firstly transformed into multiple 2D images with the same size in both time and frequency domains using Gramian angular field, Markov transition field and recurrence plot. Secondly, pixel values in images are regarded as features in vertexes of graphs, and graphs can be constructed by connecting neighbor vertexes. Finally, the GNN model is trained by constructed graphs for obtaining the fault diagnosis model of pantographs. Laboratory experiments are implemented to show the advantages of the proposed method by comparing it with other conventional methods.

Driver circuit with high-voltage pulse and high-frequency excitation for the cell of optically pumped sensors.

Helium optically pumped sensor is widely used in the application for the detection of weak magnetic fields, and the cell is the core component of that, which needs an external excitation signal to ignite and maintain its luminosity, and its luminosity affects the sensitivity performance of the sensor. To improve the performance of the cell and reduce the power consumption of the system, which is the largest power consumption component in the sensor, this study presents the design of a driver circuit for a helium cell based on a high-voltage pulse source and high-frequency excitation source and uses a T-type impedance matching circuit to realize the efficient transmission of energy. The experimental results demonstrate that the driver circuit can effectively light up the helium cell, in which the pulse voltage of the high-voltage excitation is more than 1.0kV, the output power of the high-frequency excitation signal is in the range of 0-6W, and it is easy to adjust the output power of the high-frequency excitation signal to optimize the sensitivity of the sensor with an the optimal power density of 1.1 W/cm2 and a sensitivity of 29.4 pT/Hz1/2 is obtained. The driver circuit method designed in this study is also suitable for other inert gases to generate metastable atoms.

Research on Three-Phase Wireless Power Transfer System

Aiming at the problems of low power, low energy transmission efficiency, and high stress in the circuit of a single-phase wireless power transfer system, this paper proposes a wireless power transfer (WPT) system with a three-phase angle difference of 120 degrees and establishes a COMSOL multi-physics simulation model for analysis. In this simulation model, the topology of the three-phase resonant compensation network is studied in detail, and the structure of the coupling coil is designed and adjusted. Compared with the single-phase system with the same environmental conditions, air gap, and operating frequency, the simulation results show that the proposed three-phase system can effectively reduce the magnetic flux leakage, reduce the stress in the circuit, and significantly improve the energy transmission efficiency. In order to verify the reliability of the simulation results, an experimental platform was built. The experimental results show that the efficiency and coupling degree of the new system are significantly improved at the resonant frequency of 47.5 kHz, and the stress in the circuit is also significantly reduced.

Construction of carbon sequestration ecological network in Linyi City based on supply and demand of ecosystem service.

The increasing carbon emissions is one of the important reasons for global warming. As a key area of carbon emissions, carbon sequestration capacity of cities is urgently needed to be improved. Carbon sequestration ser-vices can be transferred between supply and demand areas due to the circulation of atmosphere. With Linyi City as an example, we used the minimum cumulative resistance model to extract the matching path of supply and demand, and constructed a carbon sequestration ecological network. The results showed that the regions with high supply of carbon sequestration services were located in the north and south of the study area, and that current total supply could solve about 60% of the total demand. Although the spatial distribution of supply and demand was uneven, 54% of the areas that could meet the surrounding carbon sequestration demand were still idle. The optimized supply-demand matching paths could maintain good transmission efficiency of material and energy, with lower costs. Paths with strong potential carbon sequestration capacity were located in the central and northwest part of the research area. In the construction of carbon sequestration ecological network, it is necessary to strengthen the protection and restoration of the supply side of carbon sequestration services, realize carbon reduction and strengthen carbon sequestration on the demand side, and optimize the matching path of supply and demand. This method provided services to the demand areas through the oversupply of ecosystem services, optimized the overall resource allocation, which could advance regional carbon sequestration capacity.

Intra-Beam Interference Mitigation for the Downlink Transmission of the RIS-Assisted Hybrid Millimeter Wave System.

Millimeter-wave (mmWave) communication systems leverage the directional beamforming capabilities of antenna arrays equipped at the base stations (BS) to counteract the inherent high propagation path loss characteristic of mmWave channels. In downlink mmWave transmissions, i.e., from the BS to users, distinguishing users within the same beam direction poses a significant challenge. Additionally, digital baseband precoding techniques are limited in their ability to mitigate inter-user interference within identical beam directions, representing a fundamental constraint in mmWave downlink transmissions. This study introduces an innovative analog beamforming-based interference mitigation strategy for downlink transmissions in reconfigurable intelligent surface (RIS)-assisted hybrid analog-digital (HAD) mmWave systems. This is achieved through the joint design of analog beamformers and the corresponding coefficients at both the RIS and the BS. We first present derived closed-form approximation expressions for the achievable rate performance in the proposed scenario and establish a stringent upper bound on this performance in a large number of RIS elements regimes. The exclusive use of analog beamforming in the downlink phase allows our proposed transmission algorithm to function efficiently when equipped with low-resolution analog-to-digital/digital-to-analog converters (A/Ds) at the BS. The energy efficiency of the downlink transmission is evaluated through the deployment of six-bit A/Ds and six-bit pulse-amplitude modulation (PAM) signals across varying numbers of activated RIS elements. Numerical simulation results validate the effectiveness of our proposed algorithms in comparison to various benchmark schemes.

An optimal cooperative relay selection strategy for delay aware image transmission in large scale multi-radio multi-channel multimedia wireless sensor network

High bit-error rates and high transmission rates are required for the Multimedia Wireless Sensor Networks (MWSN) to transmit high-quality pictures through smart devices. To fully utilize the advantages of the technology known as Multiple-Input Multiple-Output, MWSN heavily relies on cooperative communication. Large-scale wireless networks use multi-radio-multi-channel to improve performance by simultaneous broadcasts across symmetrical channels to reduce interference. Expanding cooperative communication in vast networks is subject to severe interference. And, as each node in the network is mobile, routing and transmission delay pose significant problems for cooperative multimedia wireless sensor networks. Mobility increases the MWSNs’ dynamic nature, which reflects in the overhead control traffic. To address above issues, a Cluster-based Delay Aware Cooperative Relay Selection (CDACRS) was proposed by employing mobility and distance metrics and channel assignment (CA) using dynamic Global Table (GT). To minimize the end-to-end transmission latency without compromising aggregate throughput, our approach chooses a relay-node depending on the mobility and the maximum available channel capacity. Further, to improve the end-to-end energy consumption, Power Aware Transmission (PAT) protocol is developed by calculating maximum transmission power required to meet target bit error rate (BER). The proposed method’s performance is evaluated against the Cluster-based Cooperative Multi-Hop Optimal Relay Selection (CCORS); energy efficient and quality aware multi-hop cooperative image transmission; and Energy Aware Cooperative Image Transmission (EACIT) algorithms and observed that our approach improves the transmission delay by 37.5% (approx.) and end-to-end energy consumption by 48.8%.

A programmable solar‐powered radio frequency transmitter

AbstractThis paper proposes a programmable solar‐powered radio frequency (RF) transmitter. It employs a novel five‐layer structure that effectively integrates solar cells, active circuits, and broadband antenna. This design can directly emit RF signals without the need for additional power supply, enabling efficient energy conversion and transmission. In addition, a U‐shaped coupling line model is introduced to evaluate the performance of the active circuit. We fabricated a sample and measured it. The results of the measurements indicate that the proposed RF transmitter can achieve self‐powering and programmable output at any frequency within the range of 2.08–4.1 GHz, with an output power of no less than 14 dBm. Moreover, the solar cells are placed on both sides of the circuits and antenna for energy harvesting, achieving 100% sunlight insolation with a 75.5% coverage ratio. This design can be used for self‐powered green wireless system applications.

FLoRa+: Energy-efficient, Reliable, Beamforming-assisted, and Secure Over-the-air Firmware Update in LoRa Networks

The widespread deployment of unattended LoRa networks poses a growing need to perform Firmware Updates Over-The-Air (FUOTA). However, the FUOTA specifications dedicated by LoRa Alliance fall short of several deficiencies with respect to energy efficiency, transmission reliability, multicast fairness, and security. This article proposes FLoRa+ , energy-efficient, reliable, beamforming-assisted, and secure FUOTA for LoRa networks, which is featured with several techniques, including delta scripting, channel coding, beamforming, and securing mechanisms. Specifically, we first propose a joint differencing and compression algorithm to generate the delta script for processing gain, which unlocks the potential of incremental FUOTA in LoRa networks. Then, we design a concatenated channel coding scheme with outer rateless code and inner error detection to enable reliable transmission for coding gain. Afterward, we develop a beamforming strategy to avoid biased multicast and compromised throughput for power gain. Finally, we present a securing mechanism incorporating progressive hash chain and packet arrival time pattern verification to countermeasure firmware integrity and availability attacks for security gain. Experimental results on a 20-node testbed demonstrate that FLoRa+ improves transmission reliability and energy efficiency by up to 1.51× and 2.65× compared with LoRaWAN. Additionally, FLoRa+ can defend against 100% and 85.4% of spoofing and Denial-of-Service (DoS) attacks.

On the Use of Near-Field Constellation Focusing for Physical Layer Security with Extremely Large Antenna Arrays

In the fast-changing world of wireless communications, the combination of extremely large antenna arrays (ELAAs) and energy-efficient transmission methods is envisioned for the 6G. The application of directivity in the transmitted constellation can increase physical layer security (PLS) and promote the energy efficiency of transmission. In such scenarios, large constellations can be divided into multiple binary phase shift keying (BPSK) components, with each component being individually amplified and transmitted by an antenna. In this work, we consider an ELAA acting as a transmitter and constellation decomposition at the sub-array level. We investigate the impact of considering a near-field channel model in terms of secrecy rate and mutual information. In addition to the energy efficiency of the constellation decomposition, it is demonstrated that the particularities of near-field beamforming increase the PLS, namely in terms of robustness to eavesdropping.

Magnetic coupling resonant ultra‐high voltage electric vehicle wireless charging system based on parity‐time symmetry

SummaryIn recent years, the electric vehicle (EV) industry has developed rapidly, and research on wireless charging systems for the EV is very meaningful. This paper proposes a magnetic coupling resonant ultra‐high voltage EV wireless charging system based on parity‐time symmetry to meet the need of high transmission efficiency and high transmission power for the EV wireless charging system. Through the application of magnetic coupling resonance and parity‐time symmetry, the charging system can maintain constant transmission efficiency within a larger spatial range, which greatly reduces the high‐precision requirements for coil alignment. Through the proposed intelligent coil alignment system, the alignment degree of the power transmission coil, user experience, and energy transmission efficiency can be improved further, promoting the intelligence of the charging system. At the same time, an ultra‐high voltage booster module is added to the primary side of the system to provide high‐power input for the EV charging system. Simulation analysis and experiments verify the rationality and practicability of the charging system. Finally, the practical significance of the proposed system applied to power grid inspection work is discussed.